This invention relates generally to gas turbine engines and more particularly to stationary seals used in gas turbine engines.
A gas turbine engine includes a compressor that provides pressurized air to a combustor wherein the air is mixed with fuel and ignited for generating hot combustion gases. These gases flow downstream to one or more turbines that extract energy therefrom to power the compressor and provide useful work such as powering an aircraft in flight. In a turbofan engine, which typically includes a fan placed at the front of the core engine, a high pressure turbine powers the compressor of the core engine. A low pressure turbine is disposed downstream from the high pressure turbine for powering the fan.
An engine has a primary flowpath through the compressor, combustor, and turbine for hot combustion gases. There are also secondary flowpaths for various purposes, for example cooling flows, sump pressurization, etc., as well as various enclosed cavities which are isolated from the primary flowpath of the engine.
It is common in the prior art to require discourager seals at various locations within the hot section of a gas turbine engine and adjacent to the primary flowpath for purposes of preventing hot gas ingestion into the engine""s cavities. A typical discourager seal has an L-shaped cross-section including a radial leg or flange for attachment of the seal, for example in a bolted joint between two stationary structures, and an axially extending leg adjacent to the flowpath. The nature of the discourager seal function is such that the axial leg near the flowpath will operate at very high temperature, while the flanged portion is typically much cooler. The resulting thermal stresses in the axial leg, which is typically a simple cylindrical flange, can be destructive and lead to buckling or low-cycle fatigue cracking of the axial leg of the seal.
Accordingly, there is a need for a discourager seal having improved durability when exposed to high temperatures.
The above-mentioned need is met by the present invention, which provides a seal for a gas turbine engine, comprising an annular ring with an L-shaped cross-section having a radially extending leg and an axially extending leg. A plurality of corrugations are formed in the axial leg so as to make it compliant in the circumferential direction.